Powder presses



J1me 1957 c. G. CARLSON El'AL 6,

POWDER PRESSES Filed March 6, 1955 2 Sheets-Sheet 1 Fig.

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POWDER PRESSES Filed March e, 1953 2 Sheds-Sheet 2 C G. Cap 66 amZ;.TH.6pJzwLz ,9

United States rear POWDER PRESSES Carl Gustav Carlson and HermannTheodor Walter Schulz, Huskvarna, Sweden, assignors to HusqvarnaVapenfabriks Akfiebolag, Huskvarna, Sweden, a corporation of SwedenApplication March 6, 1953, Serial No. 340,818

Claims priority, application Sweden March 7, 1952 3 Claims. (Cl.18-1fi.5)

This invention relates to mechanical presses for the compaction ormolding of powder, particularly metal powder. Such presses arepreferably arranged for applying pressure both from top and from bottomwhich is essential for the production of compacts of fairly uniformdensity. This may be accomplished by means of the conventionalfriction-actuated floating die. In a more advanced die construction themovement of the die body is mechanically controlled, the die body beinglowered from a filling position into a pressing position and furtherinto an ejecting position. Such construction allows for propercoordination of punch and die move ments and a more efiective control ofthe density distribution, particularly in parts of complex shape.

The invention has for its object to provide simple and etficient meanswhereby such die constructions may be successfully incorporated inmechanical presses having a compression motion from above only, such asa singleaction eccentric press, such presses having the advantages ofhigh-speed production rates, simplicity and economy in operation, andlow maintenance costs. Another object of the invention is to provide amechanical powder metallurgy press of high flexibility in accommodatingdifferent jobs.

With the above and other objects in view, as will hereinafter appear,the invention comprises the novel combinations and arrangements of partshereinafter set forth and illustrated in the accompanying drawings, andthe advantages attained thereby will be readily understood by thoseskilled in the art.

In the accompanying drawings Fig. 1 is a schematic side view and Fig. 2a similar front view, both partly in section, of a mechanical press witha molding die assembly operated by a cam and lever arrangement. Figures3 and 4 are enlarged, vertical sectional views of the die assembly indifferent working positions. Fig. 5 is an enlarged, more detailed frontview and Fig. 6 a similar end view, partly in section on line VIVI inFig. 5, of the die operating cam. Figs. 7 and 8 are vertical crosssectional views of another molding die assembly and a coining dieassembly, respectively, which are both adapted for use in connection wththe invention. Fig. 9 is a rather schematic side view of a toggle orknuckle-joint press embodying the invention.

The press shown in Figs. 1 and 2 comprises a frame 1 with a pair ofuprights 2 and a stationary press table 3 provided with a centralopening 4 above which a die assembly may in known manner be clamped tothe table. A horizontal drive shaft 7 journaled in the uprights 2 ispreferably driven by means of a flywheel 6, possibly adapted to serve asa belt or rope pulley. In the space between the uprights the shaft isprovided with an eccentric 51, by means of an eccentric rod 52 connectedin known manner to a vertically movable press head 5 which is slidablymounted on the uprights and to which an upper punch 37 may be securedopposite the opening in the table 3. The press head may be drivendiscontinuously, for instance by providing that the shaft 7 ice isconnectible with the wheel 6 by means of a clutch operated by a pedal 56and of the well-known type automatically disconnecting after eachrevolution, the press head being each time caused to perform a downwardpressure-stroke and thereupon return to its upper position shown inFigs. 1 and 2. So far described the press may be a conventionaleccentric press, for instance for sheet metal working.

In the embodiment shown in Figs. 1 and 2 a singleacting cam disk,comprising a cylindrical disk 55 and a cam 9 mounted thereon, is securedto one end 8 of the drive shaft projecting laterally from the frame,which can disk is engaged by a roll 10 on a vertical rod 11 which isslidable in its longitudinal direction in guide pieces 12 mounted on theframe. At its lower end the rod is connected by a pair of links 13 toone arm 14 of a lever mounted to swing on a pin 15 in the frame and theother arm 16 of which is coupled by means of a pair of links 17 to thelower end of a vertical draw bar 18 which, in known manner, may bedivided into two and adjustable as to its length by means of a screwbushing 19. The draw bar is preferably positioned in a bearing 53opposite the press head 5 and movable in the vertical plane through thedrive shaft 7 together with the parts 11 and 16. The roll 10 shouldnormally engage the cam disk 9, 55 under a yielding pressure, such asthe pressure of a compression spring confined on the bar 11 and denotedby dotted lines in Fig. 2, or, better, a pneumatic pressure. To thelatter end the lever 14, 16 may, by means of a pair of links 20, beconnected to a piston 21 movable in a cylinder 22 mounted on the frameand having an air inlet at each end, the upper one preferably connectedwith some source of compressed air of substantially constant pressure.

The draw bar 18 is provided with an upper, threaded end portion 54 orother means for attachment to a vertically movable part of a dieassembly mounted on the press table 3. In the embodiment shown in Figs.1-4 this die assembly comprises a press platen 3t clamped to the table,a sleeve-shaped lower punch 31 secured to the table but, if desired,vertically adjustable, and a vertically movable die body 32 which inknown manner may be provided with a hard metal insert. By means of anumber of, preferably four, bolts or guide posts 33 vertically slidablein the platen 30, the die body is rigidly connected to a cross-piece 34provided under the platen and attached to the draw bar 18. A cylindricalcore rod 35 fixedly mounted on the cross-piece extends through theplaten and the lower punch and is situated with its upper end surface inflush with the top side of the die body. The latter is movable betweenthe powder filling position shown to the left in Fig. 3 and the ejectingposition shown in Fig. 4. In the filling position the parts 31, 32 andform together a ring-shaped die cavity 36 suiting an upper punch 37mounted on the press head 5.

For the purpose of feeding metal powder into the die cavity a plane,horizontal and, preferably, vertically adjustable support 4%) for a feedshoe 41 may be mounted between the uprights 2 in flush with the top sideof the die body when in its filling position. The shoe is movable backand forth between a receiving position shown in Fig. 1, under asubstantially funnel-shaped powder container or hopper 43, and adelivery position above the die cavity 36, the shoe being guided, forinstance, by rails 42 on the support and the die. When the shoe is notin the receiving position, the bottom of the container may beautomatically closed, for instance by a plate 44 secured to the shoe.The feed shoe may be driven mechanically from the drive shaft 7 forinstance. It may also be driven pneumatically, being connected to apiston rod 45 of a double-acting piston in a cylinder 46 mounted on theframe and having two inlets 47 con- 7 3 nected with a source ofcompressed air over some valve mechanism well-known in the art andtherefore not shown in the drawings. The valve mechanism is preferablyby mechanical or electrical transmission means operated from the shaft7, or some part driven thereby, in such a way that the feed shoeperforms a stroke forth and. back when the die has resumed its fillingposition.

' By the movement of the feed shoe over the die cavity 36 the latter iseach time .filled with substantially the same quantity of powder. Byactuating the above-mentioned clutch the upper punch is lowered to theposition shown to the right in Fig. 3, the pressing position, wherebythe powder is compressed into a compact 50 of predetermined dimensions.The shape of the cam 9 should be such that the die is lowered after theupper punch has entered the same, and obtains substantially equalamounts of moveinent relative to; both punches 31 and 37 during thepressin'g operation whereby the compact will obtain a possibly evendensity. .The latter may easily be varied by an adjustment of the mutualheight positions of the pressing tools in the pressing position, the endpositions of the upper punch being adjustable in known manner. Thecompact is removed from the die by stripping, the die being lowered bythe cam 9 into the ejecting position shown in Fig. 4 wherein the topside of the die is in flush with or somewhat below the press surface ofthe punch 31.. The cam may be shaped to lower the die continuously, butthe lowering may also be interrupted in the pressing position shown tothe right in Fig. 3, in order to continue as soon as the upper punch hasstarted moving upward. From the ejecting position the die is rapidlymoved back into the filling position, preferably before the upper punchhas reached its upper position. In so doing the die brings with it thecompact which, by the subsequent movement of the feed shoe, is pushedaway, for instance to a slooping chute not shown in the drawing,whereupon the operations described are repeated, if desiredautomatically, the driving shaft being in such case caused to rotatecontinuously.

By changing the cam disk the press may readily be adapted for theproduction of compacts of difierent shapes. In the embodimentparticularly shown in Figs. 5 and 6 the cam 9 is provided with a sideflange 70 secured to one side of the cylindrical part 55 by means ofeasily accessible bolts 71. The filling position of the die body isdetermined by the radius of the part 55 and its ejecting position by thetop 79 of cam 9. Somewhat in advance of its top 79 the cam is providedwith a part 78 of constant radius corresponding to the final compressionposition of the die body and causing the same to make 'a dwell in thisposition (the cam disk being assumed to rotate in a clockwise directionin Fig. 5). Having been passed by'the cam 9 the roll 10 generally makescontact again with the cylindrical part 55, the connecting rod 11 beingurged downwards as above described. In order to ensure an immediatereturn of the die body into the correct filling position it may,however, sometimes be advisable to provide a counter cam 75 in the pathof the roll, said cam being secured by means of bolts 76 to one side ofa disk 73 preferably having a circumferential backing flange 74 for suchcams and if desired, formed integral with the cylindrical part 55. Suchcounter cams may be used whenever it is desired to ensure an upwardmovement of the draw-bar 18. At its periphery the cam disk is preferablyprovided with a plurality of equidistant, alternative cam fasteningmeans, such as bolt holes 72, 77.

"A metal powder compact located in a die cavity may transmit or giverise to heavy frictional forces in the axial direction. It is possiblethat, during the last stage of the compression stroke, the compactedpowder can, by friction against the walls of the members 32 and 35,transmit heavy forces from the upper punch 37 to the member 32 andcross-piece 34 whereby the cam and/or the guideposts 33 could easily bedamaged. However, as the draw-bar can yield downwardly during thecompres- 4 sion stroke, there is no danger of the parts being damaged.

The invention may be used to advantage also in the production ofcompacts of a more complicated shape, also compacts having sections ofdifferent heights in the pressing direction, such as a flanged bushing,the lower punch being subdivided in corresponding, mutually movable sections. The die assembly particularly shown in Figs. 3 and 4 may'thus besubstituted by a die assembly in substantial accordance with Fig. 7which, too, comprises a press platen 86 to be fixed on the table 3, amovable die body 81, a cross-piece 82 to be attached to the drawbar 18,and guide posts 83 rigidly connecting the parts 81, 82 and slidablymounted in the press platen. The lower punch is composed of a centralsection 84 corresponding to the highest section of the compact andfixedly mounted on platen 80, and two individually movable side sections85, 86 mounted on vertical bolts 87, 88, respectively, slidably mountedin platen 8t). Cams 90 secured to the guide posts 33, for instance, areadapted to cooperate with rolls 93 on stop members 91, 92 mounted on thepress platen St and horizontally movable out of the path of punchsections 85, 86, respectively, against the action of springs 94. In thefilling position shown the punch sections 85, 86 rest on the cross-piece82 with the heads 89 of their bolts 87, 88, the composite lower punchand the die body 81 defining a fill volume 95. During compression theside sections move individually downwards until, in the final pressingposition of the die body,

piece 82 whereby alsothe punch sections 85, 86 will berestored intofilling position.

Particularly in case the lower punch is subdivided into mutually movablesections, it may be suitable in known manner to provide for a limitedyielding movement of the upper punch so that the latter rests againstthe compact under the action of a spring or the like during the ejectingoperation or an initial stage thereof. In the embodiment shown in Fig. 7a number of springs 98 are thus interposed between the upper punch 96and a part 97 secured to the press head 5, the punch being provided witha number of guide pins 99 slidably mounted in the part 97 and surroundedby the springs.

A press according to the invention may readily be changed also toperform an upwardly directed ejecting movement of a lower punch in amolding die assembly having a die body yielding in the pressingdirection, or in a coining die assembly having a stationary die. To thelatter end the draw-bar 18 may be attached to a horizontal yoke 57, Fig.8, at each end connected by links 58 to one end of a lever 59 swingablymounted on a lug 69 depending from a die adaptor or holder 64 to beclamped to the table 3. The opposite ends of the levers 59 engage a head61 on the lower end of an ejector pin 62 slidably mounted in the adaptorand operated in a downward direct-ion by a spring 66. At its upper endthe ejector pin is attached to a lower coining punch 63 situated in thestationary die 65 and cooperating with an upper punch, not shown in Fig.8, to coin or size a sintered compact 67 supported by the punch 63, inits turn supported by the adaptor 64 during coining. After coining thedraw-bar 18 is lowered by the means previously described whereby thepunch 63 is raised so as to eject the compact from the die 65.

Naturally, also other embodiments are possible within the scope of theinvention which may be applied also to mechanical presses, available orspecially built, of the types wherein the pressure is created by meansof a cam disk, a crank and/ or a toggle lever. Fig. 9 illustrates anapplication of the invention to a toggle press comprising a frame 100, astationary die table 104 and an upper, vertically reciprocating presshead 103 operated by a toggle lever 102, connected by means of a rod 115to a crank disk 116 on a rotary driving shaft 101. Mounted on alaterally projecting end of this shaft is a cam disk 105 engaged by acam follower 106 on one arm 107 of a two-armed, vertically swingablelever fulcrumed at 114. By link means 109 the opposite lever arm 108 isconnected to the upper end of a vertical connecting rod 110 slidable inguide pieces 111 on the frame and connected at its lower end by linkmeans 112 to one end of a lever 113. For the rest, the arrangement maybe similar to that shown in Figs. 1 and 2.

What we claim is:

l. A mechanical powder compacting press of the character describedcomprising a frame, a stationary table carried by the frame and havingan opening therein, a press head mounted on the frame for verticalreciprocation above the table, a horizontal driving shaft for the presshead mounted in the upper part of the frame and having one end thereofprojecting laterally from the frame, an upper punch secured to the presshead, a press platen fixedly mounted on the table above the openingtherein, a lower punch mounted on the platen opposite the upper punch, avertically movable die body above the press platen, a vertically movablecross piece below the platen, guide posts rigidly connecting the diebody and the cross piece and mounted to slide vertically in the pressplaten, a vertically movable draw-bar below the table, means connectingone end of the draw-bar to the cross piece, a radially acting camsecured to the projecting end of the drive shaft, a vertical connectingrod slidably mounted laterally of the frame, a cam follower associatedwith one end of the connecting rod and engaging the cam at a point abovethe cam, a two armed lever swingably mounted on a horizontal pivot onthe frame, a positive connection between one arm of the lever and thelower end of the connecting rod and a further positive connectionbetween the other arm of the lever and the lower end of the draw-bar,the profile of the cam imparting a downward movement to the die bodyfrom an upper powder filling position into a lower compact ejectingposition, and means operatively associated with the connecting rodurging the follower into a yielding engagement with the cam and allowingthe draw-bar to move freely downwardly during the compression stroke ofthe upper punch.

2. A press according to claim 1, comprising a counter cam extendingalong a part of the circumference of said cam and adapted to ensure anupward movement of said draw-bar and die body.

3. A mechanical powder compacting press according to claim 1 whereinsaid means operatively associated with the connecting rod urging thefollower into a yielding engagement with the cam is defined by a fluidpressure operated assembly including a cylinder carried by the frame, apiston movable in the cylinder, a piston rod connected to the piston,and connecting means between the piston rod and the arm of the leverremote from the positive connection between the lower end of the drawbarand the two armed lever.

References Cited in the file of this patent UNITED STATES PATENTS1,607,389 Claus Nov. 16, 1926 1,766,265 Smith June 24, 1930 1,820,235Lemming et al. Aug. 25, 1931 2,122,874 Whipple July 5, 1938 2,127,994Davis et al. Aug. 23, 1938 2,325,687 Kux Aug. 3, 1943 2,338,491 CutlerIan. 4, 1944 2,358,765 Stadlin Sept. 19, 1944 2,393,130 Toulmin Jan. 15,1946 2,398,227 Hubbert Apr. 9, 1946 2,457,127 Richardson Mar. 2, 19482,499,980 Stokes et al. Mar. 7, 1950 2,570,989 Seelig Oct. 9, 1951FOREIGN PATENTS 663,040 Great Britain Dec. 12, 1951

